Fluid pressure producing device



Oct'29, '1946.

L.-, E. LA BRIE FLUID rREssURE PRDUGING DEVICE 4Filgd July 21, 194s amm Patented oa. 29, 1946 2,410,169 FLUID 'PRESSURE PRODUGING DEVICE Ludger E. La Brie, Detroit, Mich., assignor to Hydraulic Brake Company, Detroit, Mich., a corporation of California Application July 21, 1943,-SerialNo. 495,638

(Cl. GL-54.6)

6 Claims.

iiuid pressure producing device operative to increase the fluid pressure through several stages Without increasing the applied operating force.

An object of the invention is to provide a fluid pressure producing device operative to effect a transition from low to high pressure Without perception to the operator.

Another object of the invention is the provision of a uid pressure producing device including a low pressure producing means, an intermediate pressure producing means, and a high pressure producing means.

A further object of theinvention is to provide a fluid pressure producing means including a low pressure chamber, an intermediate pressure chamber and a high pressure chamber, pistons.

reciprocable in the respective y chambers, and means in the pistons for controlling the transition of pressure from the low to the high pressure chamber.

A still further object of the invention is to provide a fluid pressure producing means including a cylinder having small, intermediate, and large diametral bores, a piston in the cylinder having heads reciprocable in the respective bores for producingvarious stages of fluid pressure, and a valve system inthe piston adapted to be actuated by the fluid pressure developed in the respective bores.

Other objects and advantages of the invention will appear from the following description taken L' in connection with the drawing forming part of this specication, and in Which- Fig. 1 is a diagrammatical illustration of a uid pressure braking system embodying the invention;

Fig; 2 is a vertical sectional View of a fluid pressure `producing device; and

Fig. 3 is a sectional view of a modied form of valve system-embodied in the fluid pressure producing'device.

stricted passages 66 and 68; "tion between chambers and 62 iscontrolled by Referring to the drawing for more specic details ofthe invention, I0 represents generally a. fluid pressure producing device including a cylinder I2 adapted to be mounted in a fixed position. The cylinder I2 has one end open and its other end closed as by a head I4 having secured thereto concentric cylinders I6 and I8 providing in conjunction with cylinder I2 large, intermediate and small chambers 20, 22, and 724, respectively. Cylinder I8 includes a head 26 provided with a discharge or outlet port 28 communicating with chamber 24.

Afxed to the cylinder IIJ is a suitable connection 38, normally connected to a conventional fluid reservoir or tank 32 including a passage 34 anda chamber 36 providing communication betweenthe reservoir and chamber 20 by way of passages 3`8- and 40 in the wal1 of rcylinder |72.

A piston 42 reciprocable in the chamber 20 is held against displacement by a retaining ring vi4 ysecured tothe open end of the cylinder I2.

The-piston includes a head 46, a reduced body portion 48 providing in conjunction with the lwall of the cylinder I2 an annular chamber 50,

an internal body portion 52, and a skirt' 54 supporting a sealing cup 56 for inhibiting seepage of fluid from the cylinder past the piston, and arrangedY in the back of the piston is a socket 5B. 'Chamber'EU communicates through passage 36, chamber 36 and passage 34 with reservoir 32,

The body portion 5'2 ofthe Vpiston 42 has therein inter-communicating chambers 60 and 62 communicating With chamber 50 through a passage 64, and with chamber 20 by Way of re- The communicaa spring-pressed ball check valve l0 adapted.v to be actuated by a spring-pressed slide valve 'I2 reciprocable in chamber 62.

Valve 'l2 includes a projection 'I4 for association with valve III, a projection 'I6 extended through and'beyond a bore "I8 in body portion Y52 of piston 42, the purpose of which will hereinafter appear, and an annular sectionhaving A a plurality of passages Atherethrough for control Piston 86 has in its body intercommunicating chambers and |82 corresponding to chambers 00 and 62 in piston 42. Chamber |00 is closed at one end by a ring |04 threaded in the body of the piston 88. The ring |04 receives and supports the projection 'I6 of valve 12 for reciprocation in chamber |00 and has in its wall a passage |00 providing in conjunction with a passage |08 in the body portion 52 of piston 42 communication between chambers 62 and |00.

The communication between chambers |00 and |02 is controlled by a spring-pressed ball check `valve ||0 adapted to be actuated by the uid pressure chamber 22 and also by a spring-pressed slide valve ||2 mounted for reciprocation in the chamber |02. The valve ||2 includes a plunger ||4 fitted in a bore ||6 in the head 80 of the piston 86. A restricted passage ||8 and a passage provide communication between chambers 22 and |02, passage |20 being controlled by the plunger portion of valve H2. The plunger ||4 of valve ||2 has passages |22 through its body providing communication therethrough between passage |20 and the chamber |02.

The head 00 of the piston 80 has a plurality of passages |24 therethrough providing communication between the chambers 22 and 24, and a sealing cup |26 seated on the head controls the passages |24, the central portion thereof being adapted to abut the plunger ||4 of valve ||2.

A spring |28 interposed between the sealing cup |20l and the head 20 of the cylinder i8 serves to hold the sealing cup against displacement and also to return the pistons 42 and 86 to their retracted positions. Ports |30 and |82 in the walls of the respective cylinders I0 and I8 provide communication respectively between the chambers 28 and 22, and 22 and 24 when the pistons are in retracted position.

`A fluid pressure delivery pipe or conduit |34 y connected to the discharge port 28 of the cylinder |2 has branches connected respectively to fluid pressure actuated motors |36, preferably arranged in pairs, one pair for actuating the brakes associated with the front wheels of a vehicle, and another pair associated with the brakes of the rear wheels of the vehicle.

The brakes, which may be of any desirable type, preferably include a xed support or backl ing plate |38 adapted to be secured to an axle or axle housing, a rotatable drum |40 associated with the backing plate adapted to be secured to a wheel, a pair of friction elements or shoes |42 pivoted on the backing plate for cooperation Y with the drum, a retractile spring |44 connecting the shoes, and a motor corresponding to the motors |36 mounted on the backing plate between the shoes and operative to actuate the shoes into engagement with the drum against the resistance of the retractile spring.

The socket 58 receives one end of a thrust rod |743, the other end of which is connected by a clevis |48 to a foot pedal lever |50 rockable on 4 a stub shaft |52 and connected by a retractile spring |54 to a xed support |56.

In a normal operation, upon depressing the foot pedal lever |50, force is transmitted therefrom through the rod |46, resulting in advancing the pistons 42 and 80 on the compression stroke. During the initial movement of the pistons, the sealing cup 84 on the head 46 of piston 42 closes the passage 40, the sealing cup 98 on the head 88 of the piston 86 closesoff ports |30, the sealing cup |26 on the head 90 of the piston 80 closes off port |32, and thereafter, as the pistons advance on the compression stroke, a large volume of fluid is displaced from the low pressure chamber 20 through the passages 96 in the piston head 88, past the sealing cup 98 into the intermediate pressure chamber 22, through the passages |24 on the piston head 90, past the sealing cup |20 into the high pressure chamber 24, thence through the discharge port 28 and fluid pressure delivery pipes |34 into the uid pressure actuated motors |36, causing energization of the motors with the resultant actuation of the friction ele- :ments i 42 into engagement with the drum |40 against the resistance of the retractile spring |44, to take up the clearance between the friction elements and drum. Because of the displacement of a large volume of fluid, at a relatively low pressure, the friction elements are moved into engagement with the drum quite rapidly.

After a predetermined pressure has been reached in the chamber 20, say, approximately 30 pounds per square inch, the pressure in chamber 20 acting on the ball Valve 'i0 by way of restricted passage 60 and chamber 62 cracks the valve to thereby relieve pressure from chamber 20.

The fluid pressure in the large chamber 20 is thus relieved and a portion of the fluid is returned from the chamber through restricted passage 06, chambers 62 and 60, passage 64, chamber 50, passage 38, chamber 36, and passage 34 to the reservoir 32.

Concomitantly therewith, and upon further advance of the pistons, additional pressure will be developed in the intermediate pressure chamber 22, with the consequent displacement therefrom of fluid under pressure through passages |24 in the piston head 86, past sealing cup |26` into chamber 24, thence through the discharge port 28 and fluid pressure delivery pipes into the fluid pressure actuated motors |36, causing further energization of the motors with a resultant actuation of the frictionvelements |42 into engagement with the drums to provide for greater retardation of the drums |40.

Upon the attainment of a predetermined pressure in the intermediate pressure chamber 22, say, approximately 60 pounds per square inch, the ball check valve ||0 will be .lifted from its seat and thus provide for relief of pressure from chamber 22 through restricted passage IIB, chambers |00 and |02, passage |06, passages |08, the passages in valve 12, chamber 62, past the valve 10, chamber Si), passage |54, chamber 50, passage 38, chamber 36, and passage 34 to the reservoir 32.

Simultaneously with the cracking of valvel I0 providing for relief of pressure on the fluid in chamber 22, the pressure is received on the' head 90 of the piston 85, and subsequent further movement of the pistons 42 and 86 produces the high pressure stage of operation of the unit by the development of high pressure on the fluid in chamber 24 with the consequent displacement amitiee therefrom through port28, delivery pipesv- |34 into the fluid pressure actuated motors |36, causing still further energization offthefmotors with the resultant actuation o f the friction elements-into further engagement with the drums tol thereby inhibit rotation of the drums. v

Upon attainment of a predetermined pressure, say 70 pounds per square inch, in chamber 24, actingy upon the sealing cup |26, the valve ||-2 reciprocable in chamberV |02 is moved against the resistance of the valve spring to thus abut ball valve H0, Which in turn abuts the projection 16 ofslide valve 1-2, causing movementof the valve 12 against the resistance of its spring, whereby projection i4 of the valyeabuts ballV valve 10 to retain it fromits seat. With vthe movement of the slide valves 'l2Y and H2 from their normal positions, the Vpassage 68* yin the piston 412 and the passage |20 inthe piston 36 are uncovered to thereby provide for more complete relief of" pressure from chambers, 20 and 22 through the various interconnected chambers and passages to the reservoir 32. The movement of valve 80 is insufficient to close the restricted passage 66. The complete relief of pressure in chambers 20 and 22 provides for the removal of parasitic load on the head 46 of the piston 42 and the head 86 of the piston 86 during the high uid pressure development stage of operation.

Upon completion of a braking operation, the foot pedal lever |50 is released and is returned to its retracted position under the influence of the retractile spring |54. This movement of the foot pedal lever retracts the rod |46 With the resultant release of the pistons 42 and 86 and return thereof to retracted position under the influence of retractile spring |28.

As the pistons return to retracted position, the valves 10, 12, ||0, and ||2 also return to retracted position, and simultaneously therewith a partial vacuum is created in chamber 24, resulting in drawing lluid from the reservoir through passage 34, chamber 36, and passage 38, into the annular chamber 50, thence through the passages 82 in the head of the large piston 42, past the sealing cup 84, into chamber 20, through the Dassages 96 in the head 88 of piston 86, past the sealing cup 98, into chamber 22, through the passages |24 in the head 90 of piston 86, past the sealing cup |26, into the small chamber 24, completely filling the chambers 20, 22, and 24.

During this operation iluid is returning to the chamber 24 from the fluid pressure actuated motors |36 and the fluid pressure delivery pipes |34 connecting the motors to the chamber 24. This may result in the chamber 24 receiving a quantity of fluid in excess of its capacity and in this event the excessive quantity of uid is displaced therefrom through the port |32 into the intermediate chamber 22, through port |30, into the large chamber 20, and thence through passage 40, chamber 36, passage 34, into the reservoir 32.

A modication of the valve system is illustrated in Fig. 3 wherein a piston 242 includes a body portion 252 having therein intercommunicating chambers 260 and 262 communicating with a chamber 220 by way of a restricted passage 266. The communication between the chambers is controlled by spring pressure ball check valve 210.

A piston 286 has .a body portion 292` telescoping the body portion 252 of piston 242, and provides within the body portion intercommunicating chambers 300 and 302 corresponding to chambers 260 and 262 in piston 242. Chamber 300 is 6 closed atene-end by a ring .3M-threaded in the body of piston 286 havingfa passage 306 in its wal-l and providing in conjunction with a passage 308 inthe body portion 252` of the piston 242` .communication between chambers 262 and 300.

The :communication between chambers 300 and 302 is controlled by a spring-pressed ball-check valve 3f|0V adapted to be actuated byaV springpressed valve 3|2 mounted for recprocation in chamber-302. A restricted passage-3 I6 in the piston 286-' -provides communication betweenfthe chambers222 and 302.

The mode of` operation of lthe modication is 'substantially Videntical to that of the preferred embodiment, the only difference being in they absence of the slide valve operation between the ball valveshence needs no explanation.

While this invention has been described in connection With certain specic embodiments, Vthe principle involved is susceptible ofA numerous other applications that will readily occur to perfsons skilled inthe art. The-invention is, .therefore, to be limited only as indicated by the scope oi the appended claims.

Having thus described the various features of the invention, what I claim as new and desire to secure by Letters Patent is:

1. A fluid pressure producing device having a low pressure chamber, an intermediate pressure chamber and a high pressure chamber, a piston having heads movable inthe respective chambers for creating pressure, and a loaded valve mechanism in the piston controlled by the differential of fluid pressure between the low and intermediate chambers for relieving the pressure in the intermediate pressure chamber to thereby transfer the load from the low and intermediate to the high pressure piston head.

2. A liuid pressure producing device having a low pressure chamber, an intermediate pressure chamber and a high pressure chamber, and a piston having heads movable in the respective chambers forv creating pressure, and a valve mechanism comprising a pair of ball valves and a pair of slide Valves actuated by `the fluid pressure in the chambers for consecutively relieving the pressure in the respective low and intermediate pressure chambers during ya pressure creating move- 'being first opened by a predetermined pressure in the loW pressure chamber, the Valve between the intermediate chamber and the rst :chamber being first opened by a predetermined differential of pressure between the intermediate pressure chamber and the low pressure chamber, and means to mechanically hold said valves open upon a predetermined differential between the high pressure chamber and vthe intermediate pressure chamber.

4. A fluid pressure -producing device comprising |a reservoir, a 10W pressure chamber, an intermediate pressure chamber and a high pressure chamber, a piston having heads movable in the respective chambers for creating pressure7 said low and intermediate chambers communicating with the reservoir by way of restricted passages in the piston, and loaded valves in the communication normally closing off communication,` one of said valves beingexposed on one side to the pressure of the low pressure chamber and on the other side to the pressure of the intermediate pressure chamber.

5. A uid pressure producing device having a 10W pressure chamber, an intermediate pressure chamber and a high pressure chamber, a piston having heads movable inthe respective vchambers for creating pressure, a check Valve past which said low pressure chamber communicates With the reservoir, a slide valve controlling one restricted passage from said intermediate pressure chamber to the reservoir by way of said check valve-controlled passage and said slide valve-controlled passage, said check valve normally closing the communication and adapted to be fluid pressure actuated to provide for relief of pressure from the respective 10W and intermediate pressure chambers.

6. A uid pressure producing device having a,

a slide valve adapted to be actuated by the pressure in the high pressure chamber, said rstmentioned ball .and slide valves operable to control the communication between the low pressure chamber and the reservoir, and said second-mentioned ball and slide valves operable to control the communication between the intermediate pressure chamber and the reservoir.

LUDGER E. LA BRIE. 

